XL] THE ROMAN ROADS. 73;

this was only temporary, and it was not until the year 9A.D.,
at the expiration of several hard fought campaigns, that they
finally submitted to the Romans. The necessity of keeping
them in check accounts for the subsequent maintenance of a
large force of soldiers in Pannonia, whose rebellion on receiving
the news of the death of Augustus and the accession of Tiberius
as emperor has been forcibly depicted by Tacitus1. The Danube
now became throughout its whole length the northern boundary
of the Roman empire, since Moesia, which occupied the area
that extended from its right bank to the foot of the Haemus
mountains in the lower part of its course, had been conquered
by Marcus Crassus in 29 B.C., and had been reduced not long
after to the form of a Roman province.

In the review which has thus been taken of the advances
made by the Roman arms in the regions bordering
on the civilised world during the Augustan age and
the period immediately preceding it, we see that
a considerable addition was made to the knowledge
of the face of the globe which already existed. But both in
these countries, and in those which had previously been in-
corporated in the empire, the accurate treatment of geography
was furthered by the practical spirit of the administration of the
Romans, which caused them to construct roads as means of
communication throughout their subject provinces. The object
which they had in view in this system was, no doubt, to facilitate
the passage of their armies, and to secure the rapid transmission
of intelligence to the provincial centres and to the capital itself,
and thereby to concentrate their dominion and guarantee it
against dismemberment. But, at the same time,

the careful measurement of distances which was Measurement
. . ..of Dist&nces.
thus introduced, and the clearer acquaintance with
the relative position of places and the direction followed by rivers
and mountain chains which was obtained, tended to promote
exactness in geographical study. Polybius speaks of the road
through southern Gaul from the Spanish frontier to the Rhone as
having in his time been paced, and the distances along it marked
1 Tac. Ann., i. 16 foil.